The long term objective of this study is to explain the mechanism of insulin action in the human body in order to contribute towards improvement of clinical treatment of diabetes. The specific aim of the proposed study is to delineate the mechanism by which insulin stimulates glucose transport across the plasma membranes of certain cell types. This year, we plan to establish the method by which we can consistently demonstrate glucose transport in a cell-free vesicular system. The vesicles may be prepared from broken plasma membranes by sonication or reconstitutioned from solubilized components of plasma membranes and artificial liposomes. It is hoped that the transport mechanism can be characterized better in a cell-free system than in a whole-cell system.